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JUDDER on my flash videos

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Nick BarnettJUDDER on my flash videos
by on Nov 12, 2009 at 10:58:10 am

I need help. I have a lot of flash videos on my web site When I view them on my Mac they all look fine, but if I access the site on a PC they judder like crazy.I am happy with theoverall picture quality but as it is Motorsport the movement judder is a disaster. I have now found that if I open the same files from my hard drive on the PC they still judder when opened in the FLVplayer I have - However, if I force them to open in QuickTime player on the PC they look perfect. Any ideas what is going on??
They are encoded in Sorenson using H264 (to produce MP4 files which I re name flv)
Just to make it more annoying, I can oped some You Tube files that look better. Help. Thanks Nick

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Mike SmithRe: JUDDER on my flash videos
by on Nov 12, 2009 at 4:00:53 pm

H.264 files are supported in recent versions of Flash player on both Mac and Windows.

H.264 uses complex encoding, which takes a lot of processing / graphics power to play back.

If you have big frame sizes or a large data rate your video files may make more demands than an older system can handle, resulting in choppy playback or worse - no playback, crashes - on older Windows or Mac machines, though newer and higher-spec machines should be fine (either platform).

In choosing your data rate and frame sizes from compression / distribution you no doubt will take a decision on what trade-off to make between quality and file size, and carry out tests on whatever you set as a minimum playback system you want to support, to determine how big your frame sizes and your files should be.

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Nick BarnettRe: JUDDER on my flash videos
by on Nov 12, 2009 at 4:26:24 pm

Thanks Mike. That is what I suspected.Would you have a view on the best way to go next. Within Sorenson I have the option of VP6 or Spark pro. In WMV encoding they have a slider that offers Smooth playback vs Sharp playback. but there dosn't seem to be the same controll in Flash.

Did you by chance have a look at any of the videy on - if so how did it look? It is vey difficult to know how the 'outside world' is seeing the end product.

Thanks for the help. Nick

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Mike SmithRe: JUDDER on my flash videos
by on Nov 13, 2009 at 10:22:51 am

Hi Nick

Sorry, I haven't viewed any of the video yet - it doesn't run at all on my little slow web machine. I might check it out later when I'm back at base.

What format to encode to - some people are strong advocates for one or another format, so I'll comment with caution!

Many modern systems support H264 fine, so long as the frame size is not too large and the data rate is kept down. Some are convinced that H.264 offers better results for comparable file sizes (than VP6).

VP6 is a Flash-native format, and in the words of the CCOW web master "just works". Lots of people use it for web video. In my own tests, I found that VP6 produces very similar quality results to H264 at datarates around 400 - 600 kbps and frame size 1/4 standard definition. Flv files from a Flash encoder of course can also contain Flash cue points.

The threads on these link
shows some perspectives on this

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